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banana dispersion & kick-response

banana dispersion & kick-response. Data taken during Ti8 Test on 7 th June 2009 J. Wenninger , K. Fuchsberger. Contents. Higher order dispersion Kick-response measurement and b3. Third order fits, nominal model. Dispersion derived by third order fits I. nominal model

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banana dispersion & kick-response

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  1. banana dispersion& kick-response Data taken during Ti8 Test on 7th June 2009 J. Wenninger, K. Fuchsberger

  2. Contents • Higher order dispersion • Kick-response measurement and b3

  3. Third order fits, nominal model

  4. Dispersion derived by third order fits I • nominal model • trimmed deltap-values Quite large errors in Dx Offset in Dx’, Large error at the end Huge unpredicted values For Dx’’

  5. BPM nonlinear scaling Polynomials provided by BI to apply to data from the frontends (x1, y1): x, y, x1 and y1 in mm

  6. Dispersion derived by third order fits II • nominal model • trimmed deltap-values • BPM scaling polynomials applied Dx’ better centered, but too high Dx’’ much lower

  7. Response measurement BPM gains? V response (MCIAV.80104) H response (MCIAH.80204) Vertical error increasing (phase)

  8. BPM gains • Corrector gains fixed • Dataset taken with 25 Correctors • Fit with monitor gains, kqf, kqd Average gain ~ 1.12 • This was also visible in 2004 (But for some reason not last year?)

  9. Monitor Gains in LHC? LHC S78, August 2008 (we stated ‘perfect’ ;-): But: reanalyzed and looking a little bit closer: Average gain ~ 1.10

  10. Dispersion derived by third order fits III • nominal model • trimmed deltap-values • BPM scaling polynomials applied • additional factor of 1/1.12 applied (after polynomials) Nice Dx!

  11. B3: flat-top-length dependent? • b2, deltak/k, deltap/p unrealistic, but related by transformation. b3 is independent on FT length (average = -4.68)

  12. Third order fits, model b3=-4.68

  13. Dispersion derived by third order fits IV • model with b3=-4.68 • trimmed deltap-values • BPM scaling polynomials applied • additional factor of 1/1.12 applied (after polynomials) !? b3 generates Dx’’ (although not the measured one ;-)

  14. Conclusions and open issues Preliminary Conclusions: • We can reconstruct second order dispersion which is in agreement with estimated b3 • b3 is not dependent on flat-top length Open issues: • Source for monitor gain factor (~1.1) unclear • How to fix deltap/p ?

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